The present invention relates generally to fastening systems, and more particularly to pre-assembled fastener retention members and fasteners.
It is known generally to pre-assemble a fastener in the bore of a work piece prior to mounting the work piece on a mounting surface.
U.S. Pat. No. 5,395,194 entitled xe2x80x9cConvoluted Bolt Retainer,xe2x80x9d for example, discloses a polymeric retainer having a thin wall annular body member comprising an alternate arrangement of arcuate ribs and ears about a central opening. The polymeric retainer is pre-assembled into a stepped bore in a structural member and is retained therein by elastic deformation of the retainer walls. The elastic body member retains a bolt shaft disposed in the opening thereof prior to mounting of the structural member on a mounting surface.
A disadvantage of this design, however, is that a special stepped bore is required in the structural member. As such, the retainer cannot be used with structures having conventional holes. An additional disadvantage is that fasteners constructed in accordance with the design do not adequately retain the fastener in the structure, and they have a tendency to become dislodged during shipment.
U.S. Pat. No. 6,174,118 entitled xe2x80x9cMovable Retention Device For A Threaded Fastener,xe2x80x9d discloses a threaded fastener retention device which includes a housing having a retainer aperture formed therein and tab retainers adjacent the aperture. A resilient retainer is movably mounted in the aperture. The retainer includes a body having tabs for engaging the tab retainers and fastener gripping members for engaging the threads of the fastener and retaining the fastener in the housing.
A disadvantage of this design, however, is that the retainer requires a specifically designed retainer aperture formed in a housing. The retainer cannot be effectively used in conjunction with a conventional hole. A further disadvantage of the design is that the fastener is not readily axially displaceable within the aperture. Instead, the threads of the fastener engage the fastener gripping members such that axial displacement is only possible by either turning the fastener such that the threads drive the fastener axially, or by forcing the fastener axially, thereby deforming the fastener gripping members.
While it is true that in some applications it is desirable that the fastener be held axially in position, such as, for example, in a situation where it is desirable that a leading end of the fastener shaft does not extend beyond a sealing surface of a first work piece prior to mounting thereof on the mounting surface of a second work piece, such is not always the case. For example, packaging restraints may become an issue if the captured fastener assemblies are mechanically locked in an upward position, as upward clearance may not be available. Moreover, the need for fasteners to locate blind holes prior to bolt-down while allowing minimal risk of damaging (i.e., pitting or scratching) the mounting surface further makes desirable a readily axially retractable design.
What is desired, therefore, is a fastener system which overcomes problems in and improves upon the prior art, which is reliable and economical, which may be pre-assembled with standard a fastener without modification to the fastener, which may be retained in the bore of a work piece without modification of the work piece, which allows the fastener shaft to be retracted within an opening of a work piece, while also allowing for axial movement of the fastener shaft within the opening, and which compensates for misalignment between first and second openings in corresponding work pieces to be mounted together.
Accordingly, it is an object of the present invention to provide a fastener system which overcome problems in and improve upon the prior art.
Another object of the present invention is to provide a fastener system having the above characteristics and which is reliable and economical.
A further object of the present invention is to provide a fastener system having the above characteristics and which may be pre-assembled with standard a fastener without modification to the fastener.
Still another object of the present invention is to provide a fastener system having the above characteristics and which may be retained in the bore of a work piece without modification of the work piece.
Yet a further object of the present invention is to provide a fastener system having the above characteristics and which allows the fastener shaft to be retracted within an opening of a work piece, while also allowing for axial movement of the fastener shaft within the opening.
Still yet a further object of the present invention is to provide a fastener system having the above characteristics and which compensates for misalignment between first and second openings in corresponding work pieces to be mounted together.
These and other objects of the present invention are achieved by provision of a fastener system having a fastener and a fastener retention member. The fastener includes a threaded portion, a head, and a shank portion extending therebetween. The threaded portion includes threads having a major diameter greater than a diameter of the shank portion. The fastener retention member includes a body member having an axial opening therethrough, and at least one shank engagement member protruding into the axial opening of the body member. The shank engagement members define a diameter smaller than the major diameter of the threads of the threaded portion of the fastener. The shank portion of the fastener is received in the axial opening of the fastener retention member and is axially movable therein and trapped between a position where the head of the fastener abuts the fastener retention member and a position where the threaded portion of the fastener engages the shank engagement members.
Preferably, the fastener retention member is adapted to be received in an opening of a work piece, and the fastener retention member includes at least one work piece engagement member protruding outwardly from the axial opening of the body member. Most preferably, the at least one shank engagement member comprises three shank engagement members, and the at least one work piece engagement member comprises three work piece engagement members. It is also most preferable if the fastener retention member is a unitary metal member.
It is also preferable that the fastener retention member also includes a flange protruding outwardly from the axial opening of the body member. Most preferably, the flange comprises three flange portions.
In one embodiment, the at least one shank engagement member loosely engages the shank portion of the fastener so as to allow for uninhibited axial relative movement between the fastener and the fastener retention member. In another embodiment, the at least one shank engagement member frictionally engages the shank portion of the fastener such that while axial movement is readily accomplished, there is some resistance thereto.
Moreover, it should be understood that the degree of axial movement between the fastener and the fastener retention member is dependent upon a length of the shank portion of the fastener.